Closed feed system for steam power plants



Dec. 3, 1929- J. G. WEIR 1,738,507

CLOSED FEED SYSTEM FOR STEAM POWER PLANTS Filed Augt25, 1927 3 Sheets-Sheet 1 Jamaa & fi ar.

Dec. 3, 1929.

J. G. WEIR 1,738,507 CLOSED FEED SYSTEM FOR STEAM POWER PLANTS Filed Aug. 23, 1927 3 Sheets-Sheet 2 INVENTOR. 1 /6: 2. Izmesfi,

Dec. 3, 1929. J. G. WEIR CLOSED FEED SYSTEM FOR STEAM POWER PLANTS Filed 1927 3 Sheets-Sheet 3 HUI/ENTGR. Wa'r.

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closed feed system is dispensed with.

Patented Dec. 3, 1929 warren *srarss PATENT QFFHCE JAMES GEORGE WEIR, OF CATHCART, GLASGOW, SCOTLAND, ASSIGNOR TO G. 8: J. WEIR,

I LIMITED, 013 GLASGOW, SCOTLAND CLOSED FEED SYSTEM: FOR STEAM POWER ILANTS Application filed August 23, 1927, Serial No. 214,944, and in Great Britain October 8, 1926.

The present invention relates to closed teed systems for steam power plants involving a steam generator, a steam engine (which may be a turbine), a steam condenser, and the necessary steam and feed water connections. It is particularly applicable to steam power plants in which the steam generator is of small water capacity.

The object of the present invention is to provide a simplified arrangement, giving a greater degree of stability and smoothness of working than has been heretofore obtained. The feed tank as ordinarily employed in a (A reserve feed tank is however provided.)

The great objection to a feed tank as ordinarily employed is that, being at atmospheric pressure and open to atmosphere, i gives the feed water an opportunity of taking up air. There may be further disadvantages due to space occupied, weight, and undesrable cooling of the feed water.

According to the present invention there is substituted for the usual i'eed tank, a well at the bottom of the condenser, the water capacity of this well being; sutliciently great to provide the accommodation necessary due to accumulation of feed water in the system caused by changes in the conditions of working' of the plant.

Referring to the accompanying drawings Figure 1 illustrates the carrying of the in.- vention into effect in one convenient manner and shows a steam power plant arranged in accordance with the invention.

Figure 2 shows part of a steam power plant to which the invention has been applied: it illustrates a difierent arrangement of condenser and well from that shown in Figure 1. Figur 3 shows a steam power plant composed of two units, each of which is a steam power plantas shown in Figure 1.

A well athat is, a space free of tubes is provided at the bottom of the main condenser b of the steam power plantshown in Figure 1. A water-extraction pump 0 withd 'aws the condensate from this well and delivers it to a boiler-teed pump cl which, in turn, delivers it to the steam generator 6 of the plant through a valve f controlled by a float g in the steam generator, which, in the example described, is of the small-watercapacity Water-tube type.

The normal water level in the condenser well a (that is, the water level under fullpower conditions of running the plant) and the capacity of the well are such that the water level may rise to an extent corresponding to the normal fluctuating volume of feed water without flooding the condenser tubes, and may fall to the same extent (as when meeting; a sudden demand) without depriving the water-extraction pump of the head of water necessary for its effective operation. In other words, the volume of the well between the maXimum and minimum allowable Water levels is twice that of the normal fluctuating volume.

Inthe drawings the normal water level. is indicated by the chain-line ac, and the maximum and minimum allowable water levels by the chain-lines and a respectively.

A reserve feed-water tank 7a is provided; and a connection is taken from this tank to the top of the condenser, the connection being provided with a valve controlled by a float 7; in the condenser well a. The float 7.: acts to close the valve 7 when it rises and to open the valve when it falls.

A pipe on allows of the supply oi water from the discharge of the water-entraction pump 0 to the reserve ieedtankia, a handoperated valve a being provided tor the purpose ot controlling the discharge of water to the tank. The tank h being under atmospheric pressure and the condenser under a vacuum it will be understood that whenever the valve y' is opened water is sucked from the tank into the condenser.

The reserve teed tank It is primarily a tank from which make-up feed water is supplied. When the level in the condenser well axis that corresponding to normal (i. e. full-power) conditions of running, as shown by the chain-line 0c, the valve 1' in the connection 2' between this tank and the condenser is arranged to pass only the quantity of water required for make-up teed purposes. When, however, the water level is below the normal, more than this quantity of water is passed by the valve: that is, more water is suppliedfrom the tank It than is required at the moment for make-up feed purposes, with the object of assisting to maintain the water level in the Ewell a within desirable limits. During normal running of the plant the level of water in the condenser well is substantially constant, and the correct quantity of make-up feed is being admitted to the condenser from the feed tank.

It is a known fact that with a high load on the generator and therefore with a high Q rate-of ebullition, the proportion of steam to water in the water tubes is very great, andthe total amount of water in the generator is very small with respect to the steam generated per hour. Therefore, the reduction of the amount of water in the water tubes when the enerator is steamin at a' high rate has a distinct influence on the 7 amount of water in the steam and water drum of the generator, that is, the drum in which, according to the present invention, the float g is Placed. Therefore, for the same amount of water in the generator 6 the float g is higher with a high rate of steam generation therein with a low rate, that is, it is higher with a load than with a low load.

Consequently, if the load on the steam generator 6 suddenly drops, the water level in it drops due to the consequent reduction in ebullition. The float-controlled valve f in the steam generator 6 throttling the discharge of the feed pump'd which is of the centrifugal type will then act to cause the feed pump cl to supply more water from the condenser well a and thus to bring up the water-level in the generator.

noeuvering' or standby conditions for some 'time, water in excess of .the normal fullpower steaming quantity will have accumulated in the feed system. about'by a reduction in ebullition whenthe' load drops, and the'bringing up of the gen-.

This is brought erator waterlevel bywater from the condenser well, as just V-ClBSCIlbGCl. lVhile the I condenser well'levelis below the normal, the "valve j on the feed tank connection 2' will be passing more water than is required for make-up; the level in the well will therefore yrise,:and, if standby cond tions continue, the

well level will eventually be brought up to normal. The generator water-level will now be at normal also. lVhenthe plant resumes normal working, the generator water level will rise above normal, due to the increase in I ebullition for the reason hereinbefore specified, and the generator float-controlled valve f will act to reduce the quantity of water supplied by the feed pump d. Water will therefore then accumulate in the condenser well and, as pointed out above, the well is made sufficiently large to allow of this accumulation without leading to flooding of the condenser tubes.

It will be seen that there is no feed tank as ordinarily provided in a closed feed system. Considerable economy in space is therefore attained, a feature which is of great importance in warships. The provision of a large well atthe bottom of the condenser is generally of no disadvantage as regards space provision, the necessary space usually being available.

Vhen the invention is applied to existing installations, a well or tank a is provided and is placed, as shown in Figure 2, so as to allow water to gravitate into it from the condenser I): it is connected to the condenser by a water-delivery pipe 0. This well or tank a takes the place of the well a described above with reference to Figure 1. This arrangement functions in precisely the same manner as that just described.

The invention may be applied to a steam power plant comprising two units working in parallel as shown in Figure 3. Each unit includes a steam generator, steam condenser, and boiler-feed and water-extraction pumps, together with the necessary steam and feedwater connections. The condenser Z) of each unit is provided with a well a as described above, with reference to Figure 1. \Vater may be supplied to each condenser from a common reserve feed tank It, the supply of water to each condenser being controlled by a valve actuated by a float it" in the well of that condenser. Provision is made for supplying water to the common feed tank from the discharge of the water-extraction pump of either unit.

The feed water main of one unit is connected to that of the other unit by means of cross pipes p and 8, each provided with a valve 1* and t respectively. The pipe 7) is interposed between the water extraction and boiler feed pumps 0 and (Z while the pipe 8 is positioned between the condensers b and the water extraction pumps 0. Vith such an arrangement when the water level in the condenser of one unit is higher than that in the condenser of the other unit, water will be transferred from one unit to the other upon opening of the valves in the cross pipes, owing to the diflerence in the head of the suction sides of the respective water extraction pumps. In practice, if desired, it will be understood that either one of the pipes p or 8, may be eliminated, leaving the remaining pipe to establish equalization of water level in the different units.

Having thus described my invention, what main, there being a well at the bottom of each of said condensers so placed that the condensate obtained from the condensation of steam in said condenser gravitates into it, the water capacity of this well being sui'f ticientlygreat to provide the accommodation necessary due to accumulation oi feed water in the unit caused by changes in the conditions of working of the plant-a pipe con necting together the teed water mains of the several units between said condenser and said boiler feed pump in each case, and a valve on the pipe in each case. 2. A steam power plant working on a closed feed system and consisting of a plurality of units-each including a steam generator, a steam engine operated by the steam generated in said steam generatona steam condenser for said engine, a water main for returning steam condensate from the conof said condensers so placed that the condensate obtained from the condensation of steam in said condenser gravitates into it,

the water capacity of this well being sufticiently great to providethe accom1nodation necessary due to accumulation of feed water in the unit causedby changes in the conditions of working of the plant-pipes r.:onnecting together the teed Water mains of the several units between said condenser and said boiler iieed pump in each case, and a valve on each of said pipes.

8. A steam power plant working on a closed feed system and consisting of a plurality of units-each including a steam generator, a steam engine operated by the steam generated in said steam generator, a steam condenser for said engine, a water main for returning steam condensate from the condenser to the generator, and a water extraction pump and a boiler feed pump in said main, there being a well at the bottom of each of said condensers so place-d that the condensate obtained from the condensation of steam in said condenser gravitates into it,

the water capacity of this Well being suf iiciently great to provide the accommodation necessary due to accumulation of feed water in the unit caused by changes in the conditions of working of the planta pipe connecting together the feed water mains of the several units on the discharge sides of said watenextraction pumps, and a valve on the pipe in each case.

4-. A steam power plant working on a closed feed system and consisting of a plurality of unitseach including a steam generator, a steam engine operated by the steam generated in said steam generator, a steam condenser for said engine, a water main for returning steam condensate from the condenser to the generator, and a water extraction pump and a boiler teed pump in said main, there being a well at the bottom of each of said condensers so placed that the condensate obtained from the condensation o'l steam in said condenser gravitates into it, the water capacity of this well being sutliciently great to provide the accommodation necessary due to accumulation of feed water in the unit caused by changes in the conditions of working of the alantpipes connecting together the feed water mains of the several units on the discharge sides of said water-extraction. pumps, and a valve on each oi said pipes.

5. A steam power plant working on a closed feed system and consisting of a plurality of units-each including a steam generator, a steam engine operated by the steam generated in said steam generator, a steam condenser for said engine, a water main for returning steam condensate from the condenser to the generator, and a water extrac tion pump and a boiler feed pump in said main, there being a well at the bottom of each of said condensers so placed that the condensate obtained from the condensation of steam in said condenser gravitatcs into it, the water capacity of this well being sutficiently great to provide the accommodation necessary due to accumulation of feed water in the unit caused by changes in the conditions of working of the plant-21 pipe connecting together the feed water mains oi the several units between said condenser and said boiler feed pump in each case, and a valve on the pipe in each case, a reserve teed tank, a connection from said tank to each of said condensers, and a valve on each of said connections.

6. A steam power plant working on a closed feed system and consisting of a plurality of units-each including a steam generator, a steam engine operated by the steam generated in said steam generator, a steam condenser for said engine, a water main for returning steam condensate fromthe condenser to the generator, and a water extraction pump and a boiler feed pump in said main, there being a well at the bottom of each of said condensers so placed that the tion necessary due to accumulation of feed water in the unit caused by changes in the conditions of working of the plant-pipes connecting together the feed water mains of the several units between said condenser and said boiler feed pump in each case, and a valve'on each of said pipes, a reserve feed tank, a connection from said tank to each of said'condensers, and a valve on each of said connections.

7. A steam power plant working on a closed feed system and consisting of a plurality of unitseach including a steam generator, a steam engine operated by the steam generated in said steam generator, a steam condenser for said engine, a water main for returning steam condensate from the condenserto. the generator, and a water extrac- 'tion pump and, a boiler feed .pump in said main,i=there being a well at the bottom of each ot'said condensers so placed that the condensate obtained from the condensation of steam 1n said condenser gravitates into 1t,

" main, there being a well at the bottom of r ficiently great to' provide, the accommoda the water capacity of this well being suf-v ficiently great'to provide the accommodation necessary due to accumulation of feed water in the'unit caused by changes in the conditions of working of the planta pipe connecting together the feed water mains of theseveral units between said condenser and saidboiler'feed pump in'eaeh case, and a valve on. the pipe in each case, a reserve feed tank, a connection from said tank to each of said condensers, a float in each, of said wells, and a'valve oneach of said connections, each of saidi'valves being controlled by the float in the corresponding condenser.

8. A steam power plant working on av closed feed system and consisting of a plural-.

ity of units-each including a steam generator, a steam engine operated by the steam generated in said steam generator, a steam condenser, for said engine, a water main for returning steam condensate, from the condenser to the generator, and a water extraction pump and'arboiler feed pump in said each of. said condensers so placed that the 1 condensate obtained from the condensation of steam in said condenser gravitates into it, the water capacity of this well being suttion necessary'due to accumulation of feed water in the unit caused by changes in the COIldltlOIlS' of working-of the plant-pipes 7 connecting together the feed water mains of the several units between said condenser and said b01161. feed pump in each case, and

" a valve on each of said pipes, aireserve feed,

tank, a connection from said tank to each ofsaid condensers, a float in each of said wells, and avalve on each of said connecclosed feed system and consisting of a plurality of unitseach including a steam generator, a steam engine operated by the steam generated in said steam generator, a steam condenser for said engine, a water main for returning steam condensate from the condenser to the generator, and a water extraction pump and a boiler feed pump in said main, there being a well at the bottom of each of said condensers so placed that the condensate obtained from the condensation of steam in said condenser gravitates into it, the water capacity of this well being suf ficiently great to provide the accommodation necessary due to accumulation of feed water in the unit caused by changes in the conditionsof working of the plant-a pipe connecting together the feed water mains of the several units between said condenser and said boiler ieed pump in each case, and a valve on the pipe in each case, a reserve feed tank, a connection from said tank to each of said condensers, a valve on each of said connections, connections between said feed water mains and said reserve feed tank, and a valve on each of said last-mentioned connections.

10. A steam power plant working on a closed feed system and consisting of a plurality of unitseach including a steam generator, a steam engine operated by the steam generated in said steam generator, a steam condenser for said engine, a water main for returning steam condensate from the condenser to the generator, and a water extraction'pump and a boiler feed pump in said main, there being a well at the bottom of each of said condensers so placed that the condensate obtained from the condensation of steam in said condenser gravitates into it, the water capacity 01": this well being sutficiently great to provide the accommodation necessary due to accumulation of feed water in the unit caused by changes in the conditions of working of the plant-pipes connecting together the feed water mains of the several units between said condenser and said boiler feed pump in each case, and a valve on each of said pipes, a reserve feed tank, a connection from said tank to each ot said condensers, a valve on each of said connections, connections between said feed water mains and said reserve feed tank and a valve on each of said last-mentioned connections.

I hereby sign my name to this specification.

JAMES GEORGE lVEIR.

. tions, each of said valves being controlled j] i by the float in the corresponding condenser.

-9.' A steam power plant working on a llt) 

